Data / Rankings / Population aged 18 to 64 / Counties in Montana

Counties in Montana by population aged 18 to 64

Gallatin County had the highest population aged 18 to 64 of 56 counties in 2017, at 67.6%. Garfield County had the lowest, at 51.5%. The median was 55.9% and the figure for Montana was 59.8%. Source: the U.S. Census Bureau.

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Highest67.6Gallatin County
Lowest51.5Garfield County
Median55.956 counties
Montana59.8History

Map of counties, 2017

Beaverhead County: 58.7 %Big Horn County: 53.8 %Blaine County: 55.7 %Broadwater County: 56.2 %Carbon County: 56.6 %Carter County: 53.9 %Cascade County: 59.7 %Chouteau County: 55.2 %Custer County: 57.8 %Daniels County: 53.2 %Dawson County: 58.8 %Deer Lodge County: 60 %Fallon County: 56.9 %Fergus County: 54.7 %Flathead County: 58.3 %Gallatin County: 67.6 %Garfield County: 51.5 %Glacier County: 57.1 %Golden Valley County: 52.7 %Granite County: 54.3 %Hill County: 58 %Jefferson County: 57.5 %Judith Basin County: 56 %Lake County: 54 %Lewis and Clark County: 60.4 %Liberty County: 56.1 %Lincoln County: 53.7 %McCone County: 56 %Madison County: 55.8 %Meagher County: 55 %Mineral County: 54.5 %Missoula County: 64.7 %Musselshell County: 55.9 %Park County: 60.6 %Petroleum County: 54.6 %Phillips County: 55 %Pondera County: 54.8 %Powder River County: 57 %Powell County: 64.5 %Prairie County: 52.5 %Ravalli County: 54.5 %Richland County: 61 %Roosevelt County: 55.9 %Rosebud County: 56.6 %Sanders County: 52.1 %Sheridan County: 57.4 %Silver Bow County: 60.7 %Stillwater County: 56.8 %Sweet Grass County: 54.3 %Teton County: 53.7 %Toole County: 64.3 %Treasure County: 54.1 %Valley County: 55.4 %Wheatland County: 52.6 %Wibaux County: 52.4 %Yellowstone County: 59.8 %
  • Under 54
  • 54 to 55
  • 55 to 56
  • 56 to 57
  • 57 to 60
  • 60 and over
%, 2017. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2017

Gallatin County: 67.6 %Gallatin County67.6Missoula County: 64.7 %Missoula County64.7Powell County: 64.5 %Powell County64.5Toole County: 64.3 %Toole County64.3Richland County: 61 %Richland County61Silver Bow County: 60.7 %Silver Bow County60.7Park County: 60.6 %Park County60.6Lewis and Clark County: 60.4 %Lewis and Clark County60.4Deer Lodge County: 60 %Deer Lodge County60Yellowstone County: 59.8 %Yellowstone County59.8Cascade County: 59.7 %Cascade County59.7Dawson County: 58.8 %Dawson County58.8Beaverhead County: 58.7 %Beaverhead County58.7Flathead County: 58.3 %Flathead County58.3Hill County: 58 %Hill County58Custer County: 57.8 %Custer County57.8Jefferson County: 57.5 %Jefferson County57.5Sheridan County: 57.4 %Sheridan County57.4Glacier County: 57.1 %Glacier County57.1Powder River County: 57 %Powder River County57Fallon County: 56.9 %Fallon County56.9Stillwater County: 56.8 %Stillwater County56.8Rosebud County: 56.6 %Rosebud County56.6Carbon County: 56.6 %Carbon County56.6Broadwater County: 56.2 %Broadwater County56.2Liberty County: 56.1 %Liberty County56.1Judith Basin County: 56 %Judith Basin County56McCone County: 56 %McCone County56Roosevelt County: 55.9 %Roosevelt County55.9Musselshell County: 55.9 %Musselshell County55.9Madison County: 55.8 %Madison County55.8Blaine County: 55.7 %Blaine County55.7Valley County: 55.4 %Valley County55.4Chouteau County: 55.2 %Chouteau County55.2Phillips County: 55 %Phillips County55Meagher County: 55 %Meagher County55Pondera County: 54.8 %Pondera County54.8Fergus County: 54.7 %Fergus County54.7Petroleum County: 54.6 %Petroleum County54.6Mineral County: 54.5 %Mineral County54.5Ravalli County: 54.5 %Ravalli County54.5Granite County: 54.3 %Granite County54.3Sweet Grass County: 54.3 %Sweet Grass County54.3Treasure County: 54.1 %Treasure County54.1Lake County: 54 %Lake County54Carter County: 53.9 %Carter County53.9Big Horn County: 53.8 %Big Horn County53.8Lincoln County: 53.7 %Lincoln County53.7Teton County: 53.7 %Teton County53.7Daniels County: 53.2 %Daniels County53.2Golden Valley County: 52.7 %Golden Valley County52.7Wheatland County: 52.6 %Wheatland County52.6Prairie County: 52.5 %Prairie County52.5Wibaux County: 52.4 %Wibaux County52.4Sanders County: 52.1 %Sanders County52.1Garfield County: 51.5 %Garfield County51.5Gallatin County: 67.6 %Gallatin County67.6Missoula County: 64.7 %Missoula County64.7Powell County: 64.5 %Powell County64.5Toole County: 64.3 %Toole County64.3Richland County: 61 %Richland County61Silver Bow County: 60.7 %Silver Bow County60.7Park County: 60.6 %Park County60.6Lewis and Clark County: 60.4 %Lewis and Clark County60.4Deer Lodge County: 60 %Deer Lodge County60Yellowstone County: 59.8 %Yellowstone County59.8Cascade County: 59.7 %Cascade County59.7Dawson County: 58.8 %Dawson County58.8Beaverhead County: 58.7 %Beaverhead County58.7Flathead County: 58.3 %Flathead County58.3Hill County: 58 %Hill County58Custer County: 57.8 %Custer County57.8Jefferson County: 57.5 %Jefferson County57.5Sheridan County: 57.4 %Sheridan County57.4Glacier County: 57.1 %Glacier County57.1Powder River County: 57 %Powder River County57Fallon County: 56.9 %Fallon County56.9Stillwater County: 56.8 %Stillwater County56.8Rosebud County: 56.6 %Rosebud County56.6Carbon County: 56.6 %Carbon County56.6Broadwater County: 56.2 %Broadwater County56.2Liberty County: 56.1 %Liberty County56.1Judith Basin County: 56 %Judith Basin County56McCone County: 56 %McCone County56Roosevelt County: 55.9 %Roosevelt County55.9Musselshell County: 55.9 %Musselshell County55.9Madison County: 55.8 %Madison County55.8Blaine County: 55.7 %Blaine County55.7Valley County: 55.4 %Valley County55.4Chouteau County: 55.2 %Chouteau County55.2Phillips County: 55 %Phillips County55Meagher County: 55 %Meagher County55Pondera County: 54.8 %Pondera County54.8Fergus County: 54.7 %Fergus County54.7Petroleum County: 54.6 %Petroleum County54.6Mineral County: 54.5 %Mineral County54.5Ravalli County: 54.5 %Ravalli County54.5Granite County: 54.3 %Granite County54.3Sweet Grass County: 54.3 %Sweet Grass County54.3Treasure County: 54.1 %Treasure County54.1Lake County: 54 %Lake County54Carter County: 53.9 %Carter County53.9Big Horn County: 53.8 %Big Horn County53.8Lincoln County: 53.7 %Lincoln County53.7Teton County: 53.7 %Teton County53.7Daniels County: 53.2 %Daniels County53.2Golden Valley County: 52.7 %Golden Valley County52.7Wheatland County: 52.6 %Wheatland County52.6Prairie County: 52.5 %Prairie County52.5Wibaux County: 52.4 %Wibaux County52.4Sanders County: 52.1 %Sanders County52.1Garfield County: 51.5 %Garfield County51.5
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2017 (%)Change on 2016
1Gallatin County67.6-0.1 pts
2Missoula County64.7-0.5 pts
3Powell County64.5+0.3 pts
4Toole County64.3-1.2 pts
5Richland County61-0.2 pts
6Silver Bow County60.7-0.5 pts
7Park County60.6-0.2 pts
8Lewis and Clark County60.4-0.4 pts
9Deer Lodge County60-0.6 pts
10Yellowstone County59.8-0.5 pts
11Cascade County59.7-0.3 pts
12Dawson County58.8-0.6 pts
13Beaverhead County58.7-0.4 pts
14Flathead County58.3-0.6 pts
15Hill County58-0.7 pts
16Custer County57.8-0.6 pts
17Jefferson County57.5-1.1 pts
18Sheridan County57.4-0 pts
19Glacier County57.1-0.1 pts
20Powder River County57-0.5 pts
21Fallon County56.9-0.3 pts
22Stillwater County56.8-0.9 pts
23Rosebud County56.6-0.2 pts
24Carbon County56.6-0.8 pts
25Broadwater County56.20 pts
26Liberty County56.1-0.7 pts
27Judith Basin County56-1.6 pts
28McCone County56-1.3 pts
29Roosevelt County55.9-0.7 pts
30Musselshell County55.9-0.6 pts
31Madison County55.8-0.6 pts
32Blaine County55.7-0.3 pts
33Valley County55.40 pts
34Chouteau County55.2-0.3 pts
35Phillips County55-0.6 pts
36Meagher County55-1 pts
37Pondera County54.8-0.6 pts
38Fergus County54.7-0.2 pts
39Petroleum County54.6-0.1 pts
40Mineral County54.5-0.6 pts
41Ravalli County54.5-0.5 pts
42Granite County54.3-0.7 pts
43Sweet Grass County54.3-0.1 pts
44Treasure County54.1-1.4 pts
45Lake County54-0.2 pts
46Carter County53.9-1.9 pts
47Big Horn County53.8-0.9 pts
48Lincoln County53.7-0.9 pts
49Teton County53.7-0.8 pts
50Daniels County53.2-0.5 pts
51Golden Valley County52.7-1 pts
52Wheatland County52.6-0.9 pts
53Prairie County52.5-0.8 pts
54Wibaux County52.4-0.5 pts
55Sanders County52.1-0.9 pts
56Garfield County51.5-1 pts

Other periods

About this ranking

Residents aged 18 to 64 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.

Not comparable with working-age shares for ages 15 to 64 used in EU and World Bank statistics.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Census Bureau. (2026). Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (Counties in Montana by population aged 18 to 64, 2017) [Data set]. Retrieved October 12, 2026, from https://www.census.gov/programs-surveys/popest/data/data-sets.html

MLA 9

Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Montana by population aged 18 to 64, 2017. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2017. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Counties in Montana by population aged 18 to 64, 2017. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2017.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Montana by population aged 18 to 64, 2017 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-18-64/montana-counties?period=2017 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_montana_by_2017,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Montana by population aged 18 to 64, 2017}},
  year = {2026},
  howpublished = {Data set},
  url = {https://www.census.gov/programs-surveys/popest/data/data-sets.html},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2017. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Census Bureau
TI  - Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Montana by population aged 18 to 64, 2017
PY  - 2026
DA  - 2026/06/25
PB  - U.S. Census Bureau
DB  - Invokely
UR  - https://www.census.gov/programs-surveys/popest/data/data-sets.html
L2  - https://invokely.ai/rankings/population-18-64/montana-counties?period=2017
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/montana-counties?period=2017.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest population aged 18 to 64?

Gallatin County, with 67.6% in 2017, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Garfield County, with 51.5% in 2017.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Retrieved 2026-10-12.

Population aged 18 to 64: other rankings

Counties in Montana: more rankings